Synthesis of UO2 and ThO2 doped with Gd2O3

Uranium dioxide (urania, UO2) and thorium dioxide (thoria, ThO2) doped with gadolinium oxide (gadolinia, Gd2O3) were prepared via solid-state synthesis. For Gd2O3-doped ThO2, also an alternative, semi-dry process (‘‘suspension coating’’) was applied in which Gd2O3-coated ThO2 powder was produced via suspension drying followed by calcination. The microstructure and homogeneity of the materials were investigated by ceramography, EPMA and XRD. Solid-state synthesis is a convenient method to produce Gd2O3-doped UO2. However, this route was found to be inappropriate to obtain Gd2O3-doped ThO2 with an acceptable microstructure and homogeneity. The suspension coating process reported in this work is a simple and practical method to overcome these issues.